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Home » AC Fundamentals » Comparison between Star and Delta Connections

Comparison between Star and Delta Connections

Main Different between Star and Delta Connections

Comparison between Star

(Y) and Delta (Δ) Connections

 Star (Y) Connection Delta (Δ) Connection In STAR connection, the starting or finishing ends (Similar ends) of three coils are connected together to form the neutral point. A common wire is taken out from the neutral point which is called Neutral. In DELTA connection, the opposite ends of three coils are connected together. In other words, the end of each coil is connected with the start of another coil, and three wires are taken out from the coil joints There is a Neutral or Star Point No Neutral Point in Delta Connection Three phase four wire system is derived from Star Connections (3-Phase, 4 Wires System) We may Also derived 3 Phase 3 Wire System from Star Connection Three phase three wire system is derived from Delta Connections (3-Phase, 3 Wires System) Line Current is Equal to Phase Current. i.e. Line Current = Phase Current IL = IPH Line Voltage is Equal to Phase Voltage. i.e. Line Voltage = Phase Voltage VL = VPH Line Voltage is √3 times of Phase Voltage. i.e. VL = √3 VPH Line Current is √3 times of Phase Current. i.e. IL = √3 IPH The Total Power of three phases could be found by P = √3 x VL x IL x CosФ …. Or P = 3 x VPH x IPH x CosФ The Total Power of three phases could be found by P = √3 x VL x IL x CosФ … or P = 3 x VPH x IPH x CosФ The speeds of Star connected motors are slow as they receive 1/√3 voltage. The speeds of Delta connected motors are high because each phase gets the total of line voltage In Star Connection, the phase voltage is low as 1/√3 of the line voltage, so, it needs low number of turns, hence, saving in copper. In Delta connection, The phase voltage is equal to the line voltage, hence, it needs more number of turns. Low insulation required as phase voltage is low Heavy insulation required as Phase voltage = Line Voltage. In Power Transmission, Star Connection system is general and typical to be used. In Power Distribution and industries, Delta Connection is general and typical to be used.

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1. Viksh kumar singh

Comparison bw star and delta made me understand why star delta starter is used for 3 phase ac motors.

2. Please correct – Delta Connections – 3rd point –

It should be
“Three phase three wire system is derived from Delta Connections”

not Star Connections.

In the image also.

Thank you.

• Thanks for Correction. 🙂

3. Why Star connection and Delta connection is necessary for Motors ?

• Motor starting torque is high current control in star connection that necessary star cannection

• star connection is required at the starting o motor because a motors takes 5-10 times more current at starting and if delta current is given it may start immediately but this may reduce the life of motor

• Ibrahim Fatawu

Mr Khan, Pls we are talking about star ? and delta in general here not the process of star – delta connection to start a heavy motor.
Thank u

• mr. Khan, thanks for the explanation.. it was the best way to describe it.. dont care about Ibrahim Fatawu

• Thanks for appreciation….

4. THANKS FOR GUIDE

5. i need the delta and star

Very good website

7. can any one tell me in star delta mode,, in which state motor take high or more current…. in Star or Delta

8. Thanks for the guidance…

9. Thanks SAR very good sejestion

10. I WANT TO BE THE PART OF THIS GOOD KNOWLEDGE SHARING WEB SITE.

• You are most welcome dear….

11. how do I generate neutral from delta connection

• Please provide more information… For which purpose, do you want to do that? You mean, You want a single phase supply with neutral wire from three phase (Delta) Generator or what?

12. Bhagesh meher

Thanku for guidance star and delta cannection explain

13. What is diffrence between neutral and earthing. Please give me ans

• We have already published the post… You may read it here

• neutlal return current to the source while earthing neutralize the circuit

14. Thanks for the guidance.

15. Hello all;
i need the Circuit diagram of how to turn on automatically a 3 phase Generator?

16. Thanks for the guidance.

17. HOW WILL YOU TEST THE RESISTANCE OF A STAR CONNECTED MOTOR

18. vijayaraghavan

Whether u connected in star or delta….speed doesn’t varies know…only torque differs….change the answers in difference column

19. Good day!
In our industrial electrical facilities has some motor like big cooling fan has delta connection (50HP) If we will change the motor winding connection from delta to star, is any benefit from energy Saving point of view.

20. Sir ye star me neutral kyu hota h,delta kyu nhi hota h?

21. greetings
i think the star connection is used for the distribution (to provide the single phase voltage ) , and the delta is used for transmission (higher voltage , more insulation is required but we transmit by OHTL (air is our insulator ) .
its reversed in the article i think ..or may be there is something i am missing .

Please check the last point, is this true that delta used for distribution and star used for transmission ?

23. Which type of connection os better for 25hp Motor if it is connected to power pack….. we connected in star is it ok

• Harsewak Singh

u have to operate motor in star – delta connection both, initialy 25 hp motor required more force to move its shaft but as soon as it attain some speed it an be transferred to delta. we use this type of combination above 5 h.p. motors.

24. I want to use motor for running compressor motor details 440v,60hz, and 130Amps normal working current ,power 80kw load.
Starter is DOL.
Please give advise how should I connect motor terminal in star or delta
Thanks

25. Dear sir,
can u prove why star connected motor takes low current than delta connected motor.

26. Hi! Does the imbalance between the phases can be caused by type of connection? Ex. There’s phase? 2 pole induction motor and phases have the following values of current: A=130A, B = 125A, C=120A. Why they’re not the same?

27. Between star and delta connection which of them takes a high voltage either in primary or secondary coil

28. Why delta connection is require for motor??????
In home….what kind of connection we use????

• They are single Phase motors.. And obliviously, We use Single Phase supply…

29. best comparison between delta and star connection

30. SAUMITRA PRAMANIK

There is no change in speed for both star and delta connection for induction motor Speed N = 120F/P i.e. Speed depends upon only supply frequency and No of pole in motor speed can not change due to voltage variation for Ac induction motor – star delta connection used for Ac induction motor.